The present invention relates to a terminal unit of a mobile communication system and, more particularly, to a terminal unit of the type having a vibrating device for alerting the user to an incoming call.
A mobile communication system extensively used today includes a radio pager, portable radio telephone, cordless telephone or similar terminal unit. It has been customary with such a terminal unit to alert the user to an incoming call by an alert tone which is generated by a speaker or similar sounder installed in the unit. A current trend, however, is toward the replacement of the sounder with a vibrating device such as a miniature motor in order to avoid the alert tone which is simply an annoyance to persons around the user. The vibrating device is associated with the terminal unit in such a manner as to vibrate and thereby inform the user of the arrival of a call. If the casing of the terminal unit is great enough to accommodate the vibrating device, the latter is accommodated in the former. If otherwise, the vibrating device is accommodated in an adapter which is connected to the casing of the terminal unit. The problem with the vibrating device incorporated in the casing is that the vibration cannot be surely imparted to the user due to the size of the casing, often failing to alert the user to an incoming call. Likewise, the vibrator housed in the adapter is not satisfactory since the vibration thereof cannot be sufficiently imparted to the user depending on the size of the adapter. In the light of this, the vibrator may be mounted on the outer periphery of the casing or that of the adapter to transmit the vibration thereof directly to the user. Although this kind of scheme may successfully alert the user by vibration and promote easy mounting and dismounting of the vibrator, it increases the overall dimensions of the terminal unit.